VFB doesn't load properly

Hi there,
I’ve a got a quote page on my website which doesn’t load the form properly, the calendar, radio buttons and check box doesn’t show as they should.
http://rentaband.com.br/servicos/orcamento
Nevertheless, when I refresh the page the form shows perfectly.
Any help would be highly appreciated.

Rod

http://ww.wp.xz.cn/plugins/visual-form-builder/